This invention relates in general to balloon catheters and more specifically to micro occlusion balloon catheters.
Balloon catheters have been in existence for many years and have found wide application. In general they are used whenever the occlusion of a vessel is desired such as during embolization, arteriography, preoperative occlusion, emergency control of hemorrhage, chemotherapeutic drug infusion and renal opacification procedures.
The earliest developed and perhaps the most widely used occlusion balloon catheter is a urinary catheter wherein the balloon is used for anchorage. In the 1950's occlusion balloon catheters were introduced for controlling hemorrhage, thrombosing vessels and purposeful infarction. Embolectomy/thrombectomy balloon catheters were introduced in the mid 1960's and the cardiac monitoring catheters came on the market in the 1970's.
The aforementioned catheters unfortunately have limited application. They are single lumen catheters which are only able to occlude and more importantly, they are only able to occlude large vesssels. They do not fit into small diameter vessels and may not be used for the delivery of a therapeutic and/or diagnostic agent.
To achieve both occlusion and delivery of a diagnostic and/or therapeutic agent, the prior art resorted to the use of side by side catheters or calibrated leak balloon catheters, which are a type of flow guided micro catheter. Simultaneous use of two catheters carries the inherent risk of vessel damage and thrombus formation. Moreover, their use is restricted to large diameter vessels which could accommodate two catheters. Thus there still remains the general need for a micro occlusion balloon catheter and specifically for a micro occlusion balloon catheter which has the capacity to occlude small vessels as well as infuse diagnostic and/or therapeutic agents. Hence, the development of calibrated balloon catheters. Unfortunately they too only offered a partial solution.
Calibrated leak balloon catheters were first developed in the mid 1970's by Dr. Charles Kerber. They were used in general for the treatment of cerebral vascular malformations and fistulae and specifically for the therapeutic embolization of distally located cerebrovascular lesions. These catheters comprised a single lumen with a small latex balloon attached to the catheter tip via ligature or cement. For use, the balloon was punctured in the dome with a small gauge needle to allow for the transient expansion of the balloon. Pressurization of the balloon allowed the injectate to be released. This type of catheter had two major advantages. First, when used in conjunction with an extracorporeal propulsion chamber, the antegrade intravascular displacement was assisted by blood flow. Second, it permitted injection of therapeutic embolization material while flow was reduced or stopped making for a more controlled and hence safe delivery method.
Unfortunately, however, this system as well had drawbacks. Balloon inflation could only be maintained during injection. Moreover, inflation was difficult to modulate and control because the degree of inflation was unavoidably related to the pressure of the injection and the size of the hole made by puncturing of the balloon dome. This resulted in vessel rupture, inconsistent rate and volume delivery of injectate, and clogging of the balloon puncture site with embolization material precipitating balloon rupture or failure of deflation. Still further, only liquid and/or small particles, less than approximately 250 micra in diameter, could be delivered therethrough. Still further, these catheters had the inherent drawbacks of flow directed micro catheters in general. They were subject to reduced structural integrity due to diminished catheter wall thickness and weight. This drawback led to catheter rupture, tearing or fracture. In addition, the diminished wall thickness impeded steering of the catheter during insertion which could not be remedied with the use of guidewires.
Thus there still remains the need for a structurally sound micro occlusion balloon catheter which makes controlled balloon inflation and hence occlusion possible. Moreover, there still exists the need for a structurally sound micro occlusion balloon catheter which has the capacity to occlude small vessels as well as infuse diagnostic and/or therapeutic agents. Still further, there exists the need for a structurally sound micro occlusion balloon catheter which allows for the delivery of a wide variety of therapeutic and/or diagnostic agents, including liquid and solid agents.
Large two lumen occlusion balloon catheters which allow for occlusion and the delivery of therapeutic and/or diagnostic agents are known in the art. Yet because of their size, their use is restricted to vessels having a 5-6 mm or greater diameter. Vessels which are between 1.5-5 mm in diameter have heretofore been unpenetratable by two lumen occlusion balloon catheters. Their size and configuration have made access impossible because the catheter must be simultaneously small and flexible in order to follow the tortuous path of micro vessels, yet stiff enough to allow for the insertion and advancement of the catheter to the target site in the vessel path. Notably the target site may be many feet away from the insertion site. Typical micro vessels are the cerebral, renal, coronary and hepatic vasculature.
Dilitation micro balloon catheters, as distinguished from occlusion balloon catheters, having two or three lumens are known in the art. However, as their name implies, they dilate vessels and as such cause damage to vessels. Occlusion balloon catheters on the otherhand, occlude blood flow only and do not dilate the vessels. They consequently do not disturb or injure the vessels as the dilitation balloon catheters do.
In sum, a structurally sound micro occlusion balloon catheter which blocks small vessels still does not exist. And a micro occlusion catheter which occludes and infuses a liquid and/or solid therapeutic and/or diagnostic agent is even more illusive. Yet the need for such catheters is ever increasing given the quest for noninvasive diagnostic and/or treatment procedures.